As an organic EL display device (device) there is, for example, an active-matrix type having organic EL elements and, in this organic EL display device, thin-film organic EL elements are provided on a substrate provided with TFTs (thin-film transistors). In the organic EL elements, an organic EL layer, in which a light-emitting layer is included between a pair of electrodes, is laminated, a TFT being connected to one electrode of the pair of electrodes. A voltage is applied between the pair of electrodes to cause the light-emitting layer to emit light, thereby displaying an image.
In general, in a full-color organic EL display device, organic EL elements provided with light-emitting layers for each of the three colors red (R), green (G), and blue (B) are formed to be arranged as sub-pixels on a substrate. Using TFTs, these organic EL elements are selectively caused to emit light of a desired luminance, thereby making a color image display.
In manufacturing an organic EL display device, a light-emitting layer for each organic EL element made from organic light-emitting materials emitting in each color is formed in a prescribed pattern using vacuum deposition.
Vacuum deposition uses a mask (also called a shadow mask), in which a prescribed pattern of apertures are formed. The surface of a substrate onto which deposition is to be done, with which the mask is in intimate contact, is brought into opposition with a deposition source. By passing through apertures in the mask and by being deposited on the surface to receive the deposition, deposition particles (deposition material) from the deposition source form a covering film having a prescribed pattern. The deposition is performed for each color of light-emitting layer (called consecutive deposition).
A metal mask (fine metal mask: FMM) provided with highly precise apertures is used as the mask in depositing the different layers. When this is done, there is a case in which a multilayer mask, as shown in Patent Document 1, has been used.
Additionally, in order to accommodate the deposition of finer patterns, as shown in Patent Documents 2 and 3, the use of a deposition mask in which metal and resin or the like, rather than two metals, having different rates of thermal expansion, are laminated is known.